<form action="php/c_edit.php" method="POST" data-ajax="false">
    <input type="hidden" name="client_nr" value="<?php echo $_GET['client_id']; ?>" />
    <input type="hidden" name="address_id" value="<?php echo $_GET['address_id']; ?>" />
    <h3>Auftraggeber</h3>
    <input type="text" name="client_name" id="client_name" value="<?php echo $_GET['name']; ?>" placeholder="Firma" />
    <input type="text" name="client_street" id="client_street" value="<?php echo $_GET['street']; ?>" placeholder="Straße" />
    <input type="tel" name="client_zip" id="client_zip" value="<?php echo $_GET['zip']; ?>" placeholder="Postleitzahl" />
    <input type="text" name="client_city" id="client_city" value="<?php echo $_GET['city']; ?>" placeholder="Ort" />
    <br />
    <button type="submit" data-theme="a">Speichern</button>
</form>